A data center may be defined as a location, for instance, a room, that houses computer systems arranged in a number of racks. A standard rack, for example, an electronics cabinet, is defined as an Electronics Industry Association (EIA) enclosure, 78 in. (2 meters) high, 24 in. (0.61 meter) wide and 30 in. (0.76 meter) deep. These racks are configured to house a number of computer systems, about forty (40) systems, with future configurations of racks being designed to accommodate up to eighty (80) systems. The computer systems typically include a number of printed circuit boards (PCBs), mass storage devices, power supplies, processors, micro-controllers, and semi-conductor devices, that dissipate relatively significant amounts of heat during their operation. For example, a typical computer system comprising multiple microprocessors dissipates approximately 250 W of power. Thus, a rack containing forty (40) computer systems of this type dissipates approximately 10 KW of power.
The power required to transfer the heat dissipated by the components in the racks to the cool air contained in the data center is generally equal to about 10 percent of the power needed to operate the components. However, the power required to remove the heat dissipated by a plurality of racks in a data center is generally equal to about 50 percent of the power needed to operate the components in the racks. The disparity in the amount of power required to dissipate the various heat loads between racks and data centers stems from, for example, the additional thermodynamic work needed in the data center to cool the air. In one respect, racks are typically cooled with fans that operate to move cooling air across the heat dissipating components; whereas, data centers often implement reverse power cycles to cool heated return air. The additional work required to achieve the temperature reduction, in addition to the work associated with moving the cooling fluid in the data center and the condenser, often add up to the 50 percent power requirement. As such, the cooling of data centers presents problems in addition to those faced with the cooling of the racks.
Conventional data centers are typically cooled by operation of one or more air conditioning units. For example, compressors of air conditioning units typically consume a minimum of about thirty (30) percent of the required operating energy to sufficiently cool the data centers. The other components, for example, condensers and air movers (fans), typically consume an additional twenty (20) percent of the required total operating energy. As an example, a high density data center with 100 racks, each rack having a maximum power dissipation of 10 KW, generally requires 1 MW of cooling capacity. Air conditioning units with a capacity of 1 MW of heat removal generally requires a minimum of 300 KW input compressor power in addition to the power needed to drive the air moving devices, for instance, fans and blowers. Conventional data center air conditioning units do not vary their cooling fluid output based on the distributed needs of the data center. Instead, these air conditioning units generally operate at or near a maximum compressor power even when the heat load is reduced inside the data center.
In addition, the substantially static operation of conventional vents within data centers are generally designed to operate efficiently within a relatively narrow range of heat loads. However, if electronic components are allowed to exceed rated temperatures, data corruption or damage may result. Thus, conventional cooling systems and vent configurations typically operate under worst-case scenarios. For at least these reasons, cooling air is supplied to the components at around 100 percent of the estimated cooling requirement. In this respect, conventional cooling systems often attempt to cool components that may not be operating at levels which may cause their temperatures to exceed a predetermined temperature range. Consequently, conventional data centers often incur greater startup costs for cooling systems sufficiently large to meet these cooling requirements as well as greater amounts of operating expenses than may be necessary to sufficiently cool the heat generating components contained in the data centers.
Moreover, conventional vents within data centers are typically not automatically adjustable. Rather, conventional vents in data centers are usually provided as simple open grates for always full-open operation. Occasionally, data center vents are provided as manually adjustable between full open and full closed positions. Unfortunately, however, manually adjustable vents are not very useful in quickly and efficiently adapting to the ever-changing thermodynamics within a data center. Use of conventional vents within a data center also tends to give rise to negative air flow conditions or scavenging of air from a conditioned space through one or more of the vents. In other words, there are situations in which a cooling system actually pulls, instead of pushes, air back through a vent into the plenum and out a different vent. Scavenging typically occurs at the expense of a vent that is relatively distant from the cooling system blower for the benefit of a vent located relatively proximate the blower. Such a condition is undesirable since it is typically desired to maintain neutral to positive air flow at each vent within a data center. One attempt to solve the scavenging problem is to simply increase the output of the blower. This may or may not cure the scavenging condition and definitely increases the cost of operating the cooling system and data center.
Some data center vents are designed to maintain a continuous flow rate of air therethrough. For example, some vents include fans and other mechanisms for attempting to maintain a continuous flow rate of air. Such vent devices are operated based on input from sensor readings taken in the space to be conditioned. Unfortunately, however, such devices, in and of themselves, cannot solve the scavenging problem described above. The problem remains that underfloor plenum pressure intolerably fluctuates and is unpredictable. Accordingly, such non-uniform plenum pressure typically leads to scavenging and a lack of neutral to positive airflow to racks within a data center.